Donald Trump says Iran's navy, air force and air detection systems have been "knocked out" as Israeli and US forces keep pounding targets across the country.
The US president also said most of Iran's prospective future leaders had been killed, and he acknowledged the war could lead to a "worst-case scenario" where "somebody takes over who's as bad as the previous person".
Mr Trump made the comments during his first press conference since the strikes, as Iran continued to hit back at targets across the Gulf and the US indefinitely closed several regional embassies.
"Just about everything's been knocked out" in Iran, Mr Trump told reporters at the White House.
The commander of the US Central Command, Brad Cooper, later gave more details, saying the US military had destroyed 17 Iranian ships, including a submarine, and struck nearly 2,000 targets in Iran.
In response, Iran had launched over 500 ballistic missiles and over 2,000 drones in retaliatory attacks so far, he said in a video posted to X.
"We are seeing Iran's ability to hit us and our partners is declining, while our combat power, on the other hand, is building," he added.
Mr Trump also met with German Chancellor Friedrich Merz, the first world leader to visit since the strikes.
He praised his German guest but attacked Spain, which refused to let the US use its military bases in the operation.
"We're going to cut off all trade with Spain," Mr Trump said. "We don't want anything to do with Spain."
He also criticised British Prime Minister Sir Keir Starmer, who had been reluctant to allow the US to use British bases, including in the Chagos Islands — a point of tension between the leaders in the past.
"It's taken three, four days for us to work out where we can land," Mr Trump said.
"[It] would have been much more convenient landing there as opposed to flying many extra hours.
"This is not Winston Churchill we're dealing with."
Asked about the worst-case scenario the US had planned for in Iran, he said: "I guess the worst case would be we do this and then somebody takes over who's as bad as the previous person, right?"
As for who could lead Iran in future, he said: "Most of the people we had in mind are dead."
Drone attacks force embassy closures
In response to the fierce assault, Iranian drones struck the US embassy in Saudi Arabia after previously hitting the mission in Kuwait.
Washington shut both embassies, as well as its embassy in Lebanon, and ordered non-emergency government personnel and their families to leave much of the Middle East.
Another drone slammed into a car park outside the US consulate in Dubai, Secretary of State Marco Rubio later said.
The United Arab Emirates said Iran had targeted it with 186 ballistic missiles, eight cruise missiles and 812 drones. Most were intercepted, but one ballistic missile and 57 drones struck their targets, according to figures released by the UAE's defence ministry.
Iran's capital, Tehran, was repeatedly shaken by violent explosions through the day. Israel struck the headquarters of the state broadcaster IRIB as well as an area around the city's Mehrabad airport.
The building housing Iran's Assembly of Experts, tasked with replacing supreme leader Ayatollah Ali Khamenei, was also flattened by an air attack in the city of Qom, Iranian news agencies said.
It was not immediately clear if anyone was killed, but Mr Trump said senior Iranians had died on Tuesday, local time, without giving details.
"I guess there was another hit today on the new leadership, and it looks like that was pretty substantial also," he said.
Civilians suffer in many countries
As the war widened after the Lebanese group Hezbollah launched missiles at Israel, and Israel responded by bombing parts of Lebanon, Lebanese officials said the death toll there had reached 50, with 355 wounded.
It was not clear how many were civilians, but the Lebanese health ministry said at least seven were children.
Iran's death toll has reached 787, according to the local Red Crescent.
Many Iranians have fled cities and the capital has become a ghost town.
"How long will this continue? Where are the shelters? Where is the government?" Bijan, 32, a bank employee, told the Reuters news agency by telephone from Tehran.
"Every night my wife and I hide in the basement. The whole city is empty. There is smoke and blood everywhere."
Firuzeh Seraj said she was afraid to take her 10-year-old daughter for dialysis treatment after a hospital in the capital was struck.
"World, do you see? They are killing us. Hear our voice," she said through tears from Tehran.
UN humanitarian chief Tom Fletcher said civilians were suffering in nearly a dozen countries.
"Civilians must be protected," he said in a statement. "Yet strikes are hitting homes, hospitals, and schools."
Deaths have also been recorded in Israel, Bahrain, Oman, Kuwait and the UAE.
Iran talks 'smelled fishy': US official
The White House has continued to press the case for its strikes on Iran, which have been deemed unlawful by some international law experts.
Mr Trump and his officials have so far given various reasons: that Iran was getting close to building a nuclear weapon; that it could soon have ballistic missiles that could reach the US; and that Israel was preparing to strike Iran so the US had to attack to prevent counterstrikes.
But at his White House press conference, Mr Trump offered another reason: "We were having negotiations with these lunatics [Iran], and it was my opinion that they were going to attack first."
He insisted his hand was not forced by Israel, after Mr Rubio yesterday said Israel's plan to strike meant the US had to act, too.
"If anything, I might have forced Israel's hand," Mr Trump said.
In a later briefing with media, including the ABC, senior Trump administration officials said previous efforts to deal with Iran diplomatically were not working.
"It was very clear they were just trying to buy time in order to preserve whatever they could to get past the term of President Trump in order to get to a nuclear weapon," said one official, who spoke on condition of anonymity.
"If they wanted to do a peaceful nuclear program or kind of a real deal, we offered them many ample opportunities to do that."
"It all smelled fishy," another official said of the recent negotiations with Iran. "This was all a subterfuge."
ABC/wires
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